ScaleFinder is an online interactive teaching aid designed to help musicians learn scales and modes for the guitar. Just choose the scale and key and ScaleFinder will show you the notes, perfect if you are looking for an easy way to improve your knowledge of music theory.
Another interesting feature of ScaleFinder is to graphically show relationships between scales; for a basic example try comparing the C major scale with the A minor scale.
ScaleFinder is also useful for guitar teachers as you can easily print out the scale guides to give to your students as homework.
Shown below is the Major Scale: